Presuppositions and Pronouns - Nijmegen Centre for Semantics

Modals 191
q. Thus our theory implies that there is no a priori reason to assume that
modal subordination is contingent either upon the force of the modal
expressions involved (for example, existential vs. universal) or upon their
respective ordering sources. The only requirement is that their (co-)domains
be compatible. Therefore, even modals of different types (for example,
deontic and epistemic) should be able to engage in modal subordination,
provided their domains match. The following examples corroborate these
predictions:
(37) a. You must carry an umbrella but you may leave it at the
reception.
b. Harry may carry an umbrella but he must leave it at the
reception.
The modals in (37a) have universal and existential force, respectively, while
in (37b) it is the other way round, and since modal subordination is possible
in either case, these examples confirm that the force of the modals involved
doesn't matter. Moreover, whereas most hearers would probably prefer to
construe both modals in (37a) deontically, it is clearly possible to interpret
the first modal in (37b) epistemically and the second deontically (although a
deontic-deontic reading is possible too), without thereby precluding the
possibility of modal subordination. Since it is clear that epistemic and deontic
modals involve different kinds of ordering sources, this example
corroborates the second prediction.
I predict that the possibility or impossibility of modal subordination turns
upon the constraints that modals impose upon their domains, but I have not
said anything yet about what kind of constraints might be involved here. So
what I have provided so far, strictly speaking, is merely a framework for
analysing the phenomenon of modal subordination. A comprehensive
account of modal subordination would require an in-depth analysis of all the
various types of modal expressions. This is a tall order, obviously, and it
would take me far beyond the aims of this book. So let me just discuss a
couple of examples.
As we proceed it will become clear that in analysing the restrictions on
modal subordination, tense and time are key ingredients, and I shall
therefore assume that our semantics can be extended so as to account for
temporal reference and quantification. Since it is immaterial to our purposes
what the details of such a treatment of time looks like, I shall simply assume
that a state is now a triple consisting of a world, a time point, and an
embedding function, and that the class of models is suitably restricted. As far
as I can tell, however, nothing hinges upon our adopting any particular model
of time.
Let us now take a closer look at the examples in (37). We said that in (37a)
both must and may are most likely to be read deontically. Why is modal